#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
Global System Information
"""


import os
import platform
import sys
import re

from mathics.core.expression import Expression, Integer, String, Symbol, strip_context
from mathics.builtin.base import Builtin, Predefined
from mathics import version_string
from mathics.builtin.strings import StringExpression, to_regex


class Aborted(Predefined):
    """
    <dl>
    <dt>'$Aborted'
        <dd>is returned by a calculation that has been aborted.
    </dl>
    """

    name = "$Aborted"


class ByteOrdering(Predefined):
    """
    <dl>
      <dt>'$ByteOrdering'
      <dd>returns the native ordering of bytes in binary data on your computer system.
    </dl>

    X> $ByteOrdering
     = 1

    #> $ByteOrdering == -1 || $ByteOrdering == 1
     = True
    """

    name = "$ByteOrdering"

    def evaluate(self, evaluation) -> Integer:
        return Integer(1 if sys.byteorder == "big" else -1)


class CommandLine(Predefined):
    """
    <dl>
    <dt>'$CommandLine'
      <dd>is a list of strings passed on the command line to launch the Mathics session.
    </dl>
    >> $CommandLine
     = {...}
    """

    name = "$CommandLine"

    def evaluate(self, evaluation) -> Expression:
        return Expression("List", *(String(arg) for arg in sys.argv))


class Environment(Builtin):
    """
    <dl>
      <dt>'Environment[$var$]'
      <dd>gives the value of an operating system environment variable.
    </dl>
    X> Environment["HOME"]
     = ...
    """

    def apply(self, var, evaluation):
        "Environment[var_]"
        if not isinstance(var, String):
            return
        env_var = var.get_string_value()
        if env_var not in os.environ:
            return Symbol("$Failed")
        else:
            return String(os.environ[env_var])


class Failed(Predefined):
    """
    <dl>
    <dt>'$Failed'
        <dd>is returned by some functions in the event of an error.
    </dl>

    #> Get["nonexistent_file.m"]
     : Cannot open nonexistent_file.m.
     = $Failed
    """

    name = "$Failed"


class GetEnvironment(Builtin):
    """
    <dl>
    <dt>'GetEnvironment["$var$"]'
        <dd>gives the setting corresponding to the variable "var" in the operating system environment.
    </dl>

    X> GetEnvironment["HOME"]
    = ...
    """

    def apply(self, var, evaluation):
        "GetEnvironment[var___]"
        if isinstance(var, String):
            env_var = var.get_string_value()
            tup = (
                env_var,
                "System`None"
                if env_var not in os.environ
                else String(os.environ[env_var]),
            )

            return Expression("Rule", *tup)

        env_vars = var.get_sequence()
        if len(env_vars) == 0:
            rules = [
                Expression("Rule", name, value) for name, value in os.environ.items()
            ]
            return Expression("List", *rules)


class Machine(Predefined):
    """
    <dl>
    <dt>'$Machine'
        <dd>returns a string describing the type of computer system on which the Mathics is being run.
    </dl>
    X> $Machine
     = linux
    """

    name = "$Machine"

    def evaluate(self, evaluation) -> String:
        return String(sys.platform)


class MachineName(Predefined):
    """
    <dl>
      <dt>'$MachineName'
      <dd>is a string that gives the assigned name of the computer on which Mathics is being run, if such a name is defined.
    </dl>
    X> $MachineName
     = buster
    """

    name = "$MachineName"

    def evaluate(self, evaluation):
        return String(os.uname().nodename)


class Names(Builtin):
    """
    <dl>
    <dt>'Names["$pattern$"]'
        <dd>returns the list of names matching $pattern$.
    </dl>

    >> Names["List"]
     = {List}

    The wildcard '*' matches any character:
    >> Names["List*"]
     = {List, ListLinePlot, ListPlot, ListQ, Listable}

    The wildcard '@' matches only lowercase characters:
    >> Names["List@"]
     = {Listable}

    >> x = 5;
    >> Names["Global`*"]
     = {x}

    The number of built-in symbols:
    >> Length[Names["System`*"]]
     = ...

    #> Length[Names["System`*"]] > 350
     = True
    """

    def apply(self, pattern, evaluation):
        "Names[pattern_]"
        headname = pattern.get_head_name()
        if headname == "System`StringExpression":
            pattern = re.compile(to_regex(pattern, evaluation))
        else:
            pattern = pattern.get_string_value()

        if pattern is None:
            return

        names = set([])
        for full_name in evaluation.definitions.get_matching_names(pattern):
            short_name = strip_context(full_name)
            names.add(short_name if short_name not in names else full_name)

        # TODO: Mathematica ignores contexts when it sorts the list of
        # names.
        return Expression("List", *[String(name) for name in sorted(names)])


class Packages(Predefined):
    """
    <dl>
      <dt>'$Packages'
      <dd>returns a list of the contexts corresponding to all packages which have been loaded into Mathics.
    </dl>

    X> $Packages
    = {CombinatoricaOld,ImportExport,Internal,System,XML}
    #> MemberQ[$Packages, "System"]
    = True
    """

    name = "$Packages"

    def evaluate(self, evaluation):
        return Expression(
            "List",
            *(String(name) for name in evaluation.definitions.get_package_names()),
        )


class ParentProcessID(Predefined):
    """
    <dl>
      <dt>'$ParentProcesID'
      <dd>gives the ID assigned to the process which invokes the Mathics by the operating system under which it is run.
    </dl>

    >> $ParentProcessID
     = ...

    #> Head[$ParentProcessID] == Integer
     = True
    """

    name = "$ParentProcessID"

    def evaluate(self, evaluation):
        return Integer(os.getppid())


class ProcessID(Predefined):
    """
    <dl>
      <dt>'$ProcessID'
      <dd>gives the ID assigned to the Mathics process by the operating system under which it is run.
    </dl>

    >> $ProcessID
     = ...

    #> Head[$ProcessID] == Integer
     = True
    """

    name = "$ProcessID"

    def evaluate(self, evaluation):
        return Integer(os.getpid())


class ProcessorType(Predefined):
    """
    <dl>
    <dt>'$ProcessorType'
        <dd>gives a string giving the architecture of the processor on which the Mathics is being run.
    </dl>
    X> $ProcessorType
    = x86_64
    """

    name = "$ProcessorType"

    def evaluate(self, evaluation):
        return String(platform.machine())


class ScriptCommandLine(Predefined):
    """
    <dl>
    <dt>'$ScriptCommandLine'
      <dd>is a list of string arguments when running the kernel is script mode.
    </dl>
    >> $ScriptCommandLine
     = {...}
    """

    name = "$ScriptCommandLine"

    def evaluate(self, evaluation):
        try:
            dash_index = sys.argv.index("--")
        except ValueError:
            # not run in script mode
            return Expression("List")

        return Expression("List", *(String(arg) for arg in sys.argv[dash_index + 1 :]))


class SystemID(Predefined):
    """
    <dl>
       <dt>'$SystemID'
       <dd>is a short string that identifies the type of computer system on which the Mathics is being run.
    </dl>
    X> $SystemID
     = linux
    """

    name = "$SystemID"

    def evaluate(self, evaluation) -> String:
        return String(sys.platform)


class SystemWordLength(Predefined):
    """
    <dl>
      <dt>'$SystemWordLength'
      <dd>gives the effective number of bits in raw machine words on the computer system where Mathics is running.
    </dl>
    X> $SystemWordLength
    = 64

    #> Head[$SystemWordLength] == Integer
     = True
    """

    name = "$SystemWordLength"

    def evaluate(self, evaluation):
        # https://docs.python.org/3/library/platform.html#module-platform
        # says it is more reliable to get bits using sys.maxsize
        # than platform.architecture()[0]
        size = 128
        while not sys.maxsize > 2 ** size:
            size >>= 1
        return Integer(size << 1)


class UserName(Predefined):
    """
    <dl>
      <dt>$UserName
      <dd>returns a string describing the type of computer system on which
      Mathics is being run.
    </dl>

    X> $UserName
     = rocky
    """

    name = "$UserName"

    def evaluate(self, evaluation) -> String:
        return String(os.getlogin())


class Version(Predefined):
    """
    <dl>
      <dt>'$Version'
      <dd>returns a string with the current Mathics version and the versions of relevant libraries.
    </dl>

    >> $Version
     = Mathics ...
    """

    name = "$Version"

    def evaluate(self, evaluation) -> String:
        return String(version_string.replace("\n", " "))
